Problemy stratygrafii piaskowca pstrego w północno-wschodniej części Niżu Polskiego

Abstract

STRATIGRAPHICAL PROBLEMS OF THE BUNTSANDSTEIN IN THE NORTHEASTERN PART OF THE POLISH LOWLAND AREA

Among various problems concerning stratigraphy of the Buntsandstein in the northeastern area of Poland, the problem of boundary between Zechstein and Buntsandstein is the most important one.

The boundary under consideration may be observed only in the area of the Mazury-Suwałki elevation, where the Buntsandstein directly rests on the older Palaeozoic or Precambrian formations. In the remaining area, however, where a continuity in sedimentation may be traced between Zechstein and Triassic, this problem is very difficult one.

In the area of northeastern Poland this boundary may be drawn about 10-20 m above the gypsum-anhydrite. Zechstein formations at that point where a lithological change of rocks appears in a siltstone-argillaecous problematical series. Simultaneously, there may be seen here: 1) decrease in contents of gypsum anhydrite deposits, 2) appearance of limestone intercalations and 3) occurrence of organic remains.

Higher up, about 20-30 m, a characteristic form of the Buntsandstein, i.e. Triassinella chramovi occurs in various bore holes.

The problem of boundary between the Lower and Middle Buntsandstein is here very important, too. On account of a complete lack of palaeontological data, the author is forced to accept, for the area under study, the distinct change of sedimentary type as a·sole criterion in drawing the boundary under·consideration. This change is here expressed by a considerable increase of coarse-crystalline material, by clastic sediments of various grain size, by increase of plant remains, as well as by extinguishing of chemical sedimentary processes in the central part of the basin.